\input pstfig
$
\setcoorunit{4}{1}
\psset{xunit=0.4\psyunit}
%\drawaxes{-2.6}{5}{-3}{3.2}
\drawaxes{-3.5}{4}{-1.9}{1.9}
\markxlabel{0}{\scriptstyle O}{1em}
\uput[-20](0,1){\pi}
\uput[-9](0, 0.5){\nfrac{\pi}{2}}
\uput[0](0,-0.73){\!-\nfrac{\pi}{2}}
\uput[-20](0,-1){\!-\pi}
%\psset{showpoints=true}
\psplot{ 1}{ 3}{acos(1/x)/\pinum}
\psplot{-3}{-1}{-acos(1/x)/\pinum}
\thinline
\psplot{ 1}{ 3}{-acos(1/x)/\pinum}
\psplot{-3}{-1}{acos(1/x)/\pinum}
\psplot{-3}{-1}{-acos(1/x)/\pinum+2}
\psplot{-3}{-1}{acos(1/x)/\pinum-2}
\dashline
\psline(-3, 0.5)(3, 0.5)
\psline(-3,-0.5)(3,-0.5)
\psline(-3, 1.5)(3, 1.5)
\psline(-3,-1.5)(3,-1.5)
\psline(-1,-1.0)(0,-1.0)
\psline(-1, 1.0)(0, 1.0)
$
\bye
